10.2190/B0V3-BUCR-WJFY-FVFT B0V3BUCRWJFYFVFT 1 Rainfall Patterns and Agricultural Practices 99 110 20020509 20020509 20020509 20020509 B0V3BUCRWJFYFVFT.pdf http://baywood.metapress.com/link.asp?target=contribution&id=B0V3BUCRWJFYFVFT 2 Jonathan Sands Hampshire College <p>A mechanism is proposed to account for the observed rainfall increases over forests compared to geographically similar non-forest areas. This mechanism is based on the "thermal mountain" concept advanced by Malkus and Stern in 1953. A 10 km long forest, 6°C hotter than the surrounding region, can produce a thermal mountain 1026 meters high.</p><p>The height of the thermal mountain is dependent on the prevailing windspeed, the temperature difference between the forest and the surrounding area, the absolute air temperature, and the length of the forest in the direction of the prevailing wind.</p><p>The extensive deforestation due to agricultural needs may have profound effects on the climate, especially rainfall patterns, of the farm lands and surrounding countryside.</p> W. C. Lowdermilk, <i>Conquest of the Land Through Seven Thousand Years</i>, U. S. D. A. Soil Conservation Service SCS MP-32, Washington, 38 pp., 1950. H. W. Lull, <i>An Annotated Bibliography of Watershed Management Research</i>, U. S. D. A., N. E. Forest Service Research Paper NE 48, 37 pp., 1966. G. H. T. Kimble, The Changing Climate, <i>Sci. Amr., 182</i>:4, pp. 48-53, 1950. R. 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Warren, A Study of Climate and Forests in the Ranchi Plateau, <i>Indian Forester, 100</i>, pp. 229-234, 1974. G. J. Haltiner and F. C. Martin, <i>Dynamical and Physical Meteorology</i>, McGraw-Hill, New York, 1957. H. J. Critchfield, <i>General Climatology</i>, Prentice-Hall, Inc., New Jersey, pp. 59-63, 1966. S. J. Tajchman, Evapotranspiration and Energy Balances of Forest and Field, <i>Water Resources Research, 7</i>, pp. 511-523, 1971. J. M. Brown, Effect of Clearcutting a Black Spruce Bog on Net Radiation, <i>Forest Sci., 18</i>, pp. 273-277, 1972. S. F. Federov, <i>Evaporation From Forest and Field in Years With Different Amounts of Moisture</i>, Tr. Gas. Gidrol. Inst., <i>123</i>, pp. 337-347, 1965. J. S. Malkus and M. E. Stern, The Flow of a Stable Atmosphere Over a Heated Island. Part I, <i>J. Meteorol., 10</i>, pp. 30-41, 1953. M. E. Stern and J. S. Malkus, The Flow of a Stable Atmosphere Over a Heated Island, Part II, <i>J. Meteorol., 10</i>, pp. 105-120, 1953. M. E. Stern, Theory of the Mean Atmospheric Perturbations Produced by Differential Surface Heating, <i>J. Meteorol., 11</i>, pp. 495-502, 1954. J. S. Malkus, On the Isolation of Tractable Problems and an Example in Variable Heating, <i>Science Progress, 43</i>, pp. 461-475, 1955. J. F. Black and B. L. Tarmy, The Use of Asphalt Coatings to Increase Rainfall, <i>J. Appl. Meteorol., 2</i>, pp. 557-564, 1963. J. Otterman, Baring High-Albedo Soils by Overgrazing: A Hypothesised Desertification Mechanism, <i>Science, 186</i>, pp. 531-533, 1974. J. S. Oguntoyinbo, Land-Use and Reflection Coefficient (Albedo) Map for Southern Parts of Nigeria, <i>Agric. Meteorol, 13</i>, pp. 227-237, 1974. J. L. Monteith, The Reflection of Shortwave Radiation by Vegetation, <i>Quart. J. Roy. Meteorol. Soc., 88</i>, pp. 508-521, 1959. O. Draz, <i>Management and Rehabilitation of the Natural Grazing Lands</i>, Presented at the Regional Sheep and Forage Production Workshop, Beirut, February 11-14, 1974. J. T. Curtis, The Modification of Mid-Latitude Grasslands and Forests by Man, T. R. Detwyler (ed.), <i>Man's Impact on Environment</i>, McGraw-Hill, New York, 1971. Anon, The Outlook for Timber in the United States, <i>Forest Service</i>, U. S. D. A., FRR-20, 374 pp., 1974. B. Lykowski, Reflection of Solar Radiation by Vegetation, <i>Ekologia Polska, 18</i>, pp. 211-223, 1970. D. R. Dewall and S. G. McGuire, Albedo Variations of an Oak Forest in Pennsylvania, <i>Agric. Meteorol., 11</i>, pp. 107-113, 1973. L. C. Nkemdirm, Radiative Flux Relations Over Crops, <i>Agric. Meteorol., 11</i>, pp. 229-242, 1972. I. Dirnhirm and G. H. Belt, Variation of Albedo of Selected Sagebrush Range in the Intermountain Region, <i>Agric. Meteorol., 9</i>, pp. 51-61, 1971. J. D. Kalma and R. Badham, The Radiation Balance of a Tropical Pasture, I. The Reflection of Shortwave Radiation, <i>Agric. Meteorol., 10</i>, pp. 251-259, 1972. S. M. 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